Functions for Sholl analysis of neuronal skeletons

```
sholl_analysis(
x,
start = colMeans(xyzmatrix(x)),
starting.radius = radius.step,
ending.radius = 1000,
radius.step = ending.radius/100
)
# S3 method for neuron
sholl_analysis(
x,
start = colMeans(xyzmatrix(x)),
starting.radius = radius.step,
ending.radius = 1000,
radius.step = ending.radius/100
)
# S3 method for neuronlist
sholl_analysis(
x,
start = colMeans(xyzmatrix(x)),
starting.radius = radius.step,
ending.radius = 1000,
radius.step = ending.radius/100
)
```

- x
a neuron or neuronlist object

- start
the origin from which spheres are grown for the Sholl analysis

- starting.radius
the radius of the first sphere. Defaults to the radius step

- ending.radius
the radius of the last sphere. If NULL the distance to the furthest dendritic point from the start point is taken

- radius.step
the change in radius between successive spheres. Defaults to one 100th of the radius of the ending sphere

a data.frame of spheres radii and the number of dendritic intersections at each radius

```
if (FALSE) {
# Calculate how much some neurons overlap with one another
## Example requires the package nat.flybrains
Cell07PNs_sholl = sholl_analysis(x = Cell07PNs, radius.step = 1, ending.radius = 100)
head(Cell07PNs_sholl[[1]])
}
```